Question Number 24893 by sushmitak last updated on 28/Nov/17
$$\mathrm{About}\:\mathrm{a}\:\mathrm{collision}\:\mathrm{which}\:\mathrm{of} \\ $$$$\mathrm{the}\:\mathrm{following}\:\mathrm{are}\:\mathrm{not}\:\mathrm{correct} \\ $$$$\mathrm{a}.\:\mathrm{Physical}\:\mathrm{touch}\:\mathrm{is}\:\mathrm{a}\:\mathrm{must} \\ $$$$\mathrm{b}.\:\mathrm{Particles}\:\mathrm{cannot}\:\mathrm{change} \\ $$$$\mathrm{c}.\:\mathrm{Effect}\:\mathrm{of}\:\mathrm{external}\:\mathrm{force}\:\mathrm{is}\:\mathrm{not}\:\mathrm{considered} \\ $$$$\mathrm{d}.\:\mathrm{Momentum}\:\mathrm{may}\:\mathrm{or}\:\mathrm{may}\:\mathrm{not}\:\mathrm{change} \\ $$$$\mathrm{multi}−\mathrm{correct}\:\mathrm{question} \\ $$
Commented by ajfour last updated on 28/Nov/17
$${Physical}\:{touch}\:{may}\:{not}\:{be}\:{must}, \\ $$$${say}\:{in}\:{case}\:{of}\:{charges}. \\ $$$${Particles}\:{do}\:{change}\:{in}\:{say} \\ $$$${completely}\:{inelastic}\:{collision}. \\ $$$${so}\:{not}\:{correct}. \\ $$$${external}\:{force}\:{shouldn}'{t}\:{be}\:\: \\ $$$${considered}\:{and}\:{momentum} \\ $$$${should}\:{not}\:{change}\:{if}\:{system}\: \\ $$$${boundary}\:{is}\:{so}\:{chosen}\:{as}\:{to} \\ $$$${permit}\:{these}. \\ $$
Commented by sushmitak last updated on 28/Nov/17
$$\mathrm{Thanks}\:\mathrm{you}\:\mathrm{very}\:\mathrm{much}\:\mathrm{Sir}\:\mathrm{for} \\ $$$$\mathrm{the}\:\mathrm{explaination}. \\ $$